Benjamin's Space

The Yellowstone Supervolcano had it's biggest eruption 2.1 million years ago which deposited the Huckleberry Ridge ash bed although it's regular eruption cycle is every 600,000 years (give or take a few tens of thousands!). According to the geological record it last erupted 640,000 years ago and so it is due (or overdue if you go by the exact figure) for another eruption. Parts of Yellowstone have risen by aroun 70cm in the last 100 years which can be an indication of iniment volcanic activity. However, volcanoes do have a habit of stiring an then going back to sleep again before erupting years or hundreds of years later so this is just an indication the volcano is still active.

The probability of a large caldera-forming eruption within the next few thousand years at Yellowstone is exceedingly low. More likely in Yellowstone than a large explosive caldera-forming eruption is eruption of a lava flow, which would be far less devastating. Since Yellowstone’s last caldera-forming eruption 640,000 years ago, about 30 eruptions of rhyolitic lava flows have nearly filled the Yellowstone Caldera. Each day, visitors to the park drive and hike across the lavas that fill the caldera, most of which were erupted since 160,000 years ago, some as recently as about 70,000 years ago. These extensive rhyolite lavas are very large and thick, and some cover as much as 130 square miles (340 km2), twice the area of Washington, D.C. During eruption, these flows oozed slowly over the surface, moving at most a few hundred feet per day for several months to several years, destroying everything in their paths.